L 28.1 Levels of organisation

L 28.1 Levels of Organization

* Learning Outcomes: • Describe cell specialization and levels of organization. • Identify how levels of organization work together in an organism.

STARTER: Pairs Think about the way employees in a large company are organized. How would you describe the relationship between different jobs, divisions, and levels of responsibility in a company?

Multicellular organisms are made up of cells, but different cells in the organism have different functions. Take a moment to study the images of the blood cells and nerve cells, or neurons.How do you think these differences contributes to the cell's function? Discuss with your partner.

Cell specialization involves two main steps: determination and differentiation. The cells produced during the first few divisions of the zygote are known as embryonic stem cells. These cells have the potential to become any type of specialized cell in the body.

Determination It occurs in which most stem cells become committed to develop into only one type of cell. For instance, a stem cell might become a cardiac muscle cell or a spinal neuron. These committed cells still retain all of the genetic information needed to build an entire organism. However, during determination, they lose their ability to express some of this information. Once a cell is committed to becoming a specialized cell, it will develop into only that type of cell.

Differentiation Differentiation is the process by which committed cells acquire the structures and functions of highly specialized cells. Differentiation occurs because specific genes in each cell are turned on and off in a complex, regulated pattern. The different structures of these specialized cells, such as those shown in FIGURE 1.2, allow them to perform specific functions within the body. Task: In your group give one example of how specialization help cells perform a specific function.

Question: With your partner, answer the following question and upload your answer to the provided link.How does the process of cell determination differ from the process of cell differentiation?http://padlet.com/Reema_Albitar/3byv2cogz5pq

Levels of Organization Specialized, or differentiated, cells are only the first level of organization in a multicellular organism. Scientists organize multicellular structures into five basic levels, beginning with cells and moving to increasingly complex levels— tissues, organs, organ systems, and the whole organism. Refer to the flash cards below to identify each of the levels.

Search: {5 min.} The human body, with its five levels of organization, can be compared to the structure of an ecosystem with its different levels of organisation. explore this analogy.....use the internet. Provide a written explanation.

All levels of organization interact and work together to maintain the body’s health. (Fig. 1.3 pg. 801)

- Assessment:Complete the questions in the class worksheet and upload to Showbie by the end of the session.